Workers will now need the Government's controversial ID card for new benefits promised by Taoiseach Leo Varadkar.

The range of public services requiring the Public Services Card (PSC) is growing.

Despite mounting concern over the roll-out of the scheme, a number of Government minsters are refusing to answer questions about what exactly it will be needed for.

They have also failed to provide assurance to those who fear their personal information is at risk.

Civil liberty campaigners and legal experts raised questions about the legal basis on which the card is being made mandatory for certain state services.

Now it has been confirmed that the PSC will be required to check an applicant's eligibility for the new dental and optical benefits Mr Varadkar secured as social protection minister in last year's Budget.

From October, millions of people covered by PRSI will be entitled to apply for these treatment benefits, including an annual tooth polish and free spectacles.

The Department of Social Protection last night confirmed people will be required to have a PSC to check their eligibility for the benefits online.

The same department is strictly enforcing a requirement for people claiming payments, such as the state pension, to have the cards. But it is allowing some leeway with the new treatment benefits.

Dentists and opticians will still be permitted to check the patient's eligibility if they don't have a card.

In a further complication, it's been confirmed that all passport applicants in the Republic will need a PSC, however, there are "no plans" for this requirement for those from Northern Ireland or overseas.

Liam Herrick, of the Irish Council for Civil Liberties (ICCL), said it is concerned the PSC will "morph" into a national ID card.

He raised fears that such cards bring the potential to compromise individuals' privacy and the security of their personal information.

Trinity College law professor Dr Eoin O'Dell claimed the introduction of the PSC is happening "by stealth".

He argued that it protects citizens and the State from "anyone wrongly claiming something funded by the taxpayer".

He said he doesn't think "people should have any reason to fear it" and denied the PSC is a national ID card, pointing out citizens are not required by law to carry it and Gardaí can't demand that it's produced.

The controversy over the PSC blew up last week when it emerged that a woman in her 70s, who refused to register for the card, had her pension cut off.